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Ilkka S. O. Matero - One of the best experts on this subject based on the ideXlab platform.
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non invasive geophysical investigation and thermodynamic analysis of a palsa in lapland northwest finland
arXiv: Geophysics, 2014Co-Authors: Tomas Kohout, Kai Rasmus, Matti Leppäranta, Ilkka S. O. Matero, Michal S BuckoAbstract:Non-invasive geophysical prospecting and a thermodynamic model were used to examine the Structure, Depth and lateral extent of the frozen core of a palsa near Lake Peeraj\"arvi, in northwest Finland. A simple thermodynamic model verified that the current climatic conditions in the study area allow sustainable palsa development. A ground penetrating radar (GPR) survey of the palsa under both winter and summer conditions revealed its internal Structure and the size of its frozen core. GPR imaging in summer detected the upper peat/core boundary, and imaging in winter detected a deep reflector that probably represents the lower core boundary. This indicates that only a combined summer and winter GPR survey completely reveals the lateral and vertical extent of the frozen core of the palsa. The core underlies the active layer at a Depth of ~0.6 m and extends to about 4 m Depth. Its lateral extent is ~15 m x ~30 m. The presence of the frozen core could also be traced as minima in surface temperature and ground conductivity measurements. These field methods and thermodynamic models can be utilized in studies of climate impact on Arctic wetlands.
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Non‐Invasive Geophysical Investigation and Thermodynamic Analysis of a Palsa in Lapland, Northwest Finland
Permafrost and Periglacial Processes, 2014Co-Authors: Tomas Kohout, Michał S. Bućko, Kai Rasmus, Matti Leppäranta, Ilkka S. O. MateroAbstract:Non-invasive geophysical prospecting and a thermodynamic model were used to examine the Structure, Depth and lateral extent of the frozen core of a palsa near Lake Peerajarvi in northwest Finland. A simple thermodynamic model verified that the current climatic conditions in the study area allow sustainable palsa development. A ground penetrating radar (GPR) survey of the palsa under both winter and summer conditions revealed its internal Structure and the size of its frozen core. GPR imaging in summer detected the upper peat/core boundary, and imaging in winter detected a deep reflector that probably represents the lower core boundary. This indicates that only a combined summer and winter GPR survey completely reveals the lateral and vertical extent of the frozen core of the palsa. The core underlies the active layer at a Depth of ~ 0.6 m and extends to about 4 m Depth. Its lateral extent is ~ 15 m x ~ 30 m. The presence of the frozen core could also be traced as minima in surface temperature and ground conductivity measurements. These field methods and thermodynamic models can be utilised in studies of climate impact on Arctic wetlands. Copyright © 2014 John Wiley & Sons, Ltd.
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non invasive geophysical investigation and thermodynamic analysis of a palsa in lapland northwest finland
Permafrost and Periglacial Processes, 2014Co-Authors: Tomas Kohout, Kai Rasmus, Matti Leppäranta, Ilkka S. O. Matero, Michal S BuckoAbstract:Non-invasive geophysical prospecting and a thermodynamic model were used to examine the Structure, Depth and lateral extent of the frozen core of a palsa near Lake Peerajarvi in northwest Finland. A simple thermodynamic model verified that the current climatic conditions in the study area allow sustainable palsa development. A ground penetrating radar (GPR) survey of the palsa under both winter and summer conditions revealed its internal Structure and the size of its frozen core. GPR imaging in summer detected the upper peat/core boundary, and imaging in winter detected a deep reflector that probably represents the lower core boundary. This indicates that only a combined summer and winter GPR survey completely reveals the lateral and vertical extent of the frozen core of the palsa. The core underlies the active layer at a Depth of ~ 0.6 m and extends to about 4 m Depth. Its lateral extent is ~ 15 m x ~ 30 m. The presence of the frozen core could also be traced as minima in surface temperature and ground conductivity measurements. These field methods and thermodynamic models can be utilised in studies of climate impact on Arctic wetlands. Copyright © 2014 John Wiley & Sons, Ltd.
N Dietz - One of the best experts on this subject based on the ideXlab platform.
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surface characterization of cuins sub 2 with lamellar morphology
Journal of The Electrochemical Society, 1995Co-Authors: Sandro Cattarin, Cesare Pagura, Renzo Bertoncello, Lidia Armelao, N DietzAbstract:Lamellar crystals of CuInS{sub 2} grown in a steep temperature gradient have been characterized. Dispersive X-ray analyses show a predominant stoichiometry Cu/In/S = 1/1/2 and inclusions of Cu deficient phases. The cleaved surface is smooth, but after chemical etching a fine Structure appears, with a great number of closely packed microcrystals of a dendritic shape. X-ray diffraction spectra of lamellae only show the reflections of the CuInS{sub 2} (112) and of the CuIn{sub 5}S{sub 8} (111) lattice planes, indicating a strongly oriented Structure. Depth profiles of CuInS{sub 2} lamellae investigated with X-ray photoelectron spectroscopy show the presence at the cleaved surface of Cu deficient phases like CuIn{sub 5}S{sub 8}, which are a few tens of nanometers thick. The lamellar growth mechanism is discussed on the basis of these findings. X-ray photoelectron spectroscopy and secondary ion mass spectrometry investigations show that the oxidation behavior of the lamellar material resembles that of traditional CuInX{sub 2} phases (X = S, Se).
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Surface characterization of CuInS{sub 2} with lamellar morphology
Journal of The Electrochemical Society, 1995Co-Authors: Sandro Cattarin, Cesare Pagura, Renzo Bertoncello, Lidia Armelao, N DietzAbstract:Lamellar crystals of CuInS{sub 2} grown in a steep temperature gradient have been characterized. Dispersive X-ray analyses show a predominant stoichiometry Cu/In/S = 1/1/2 and inclusions of Cu deficient phases. The cleaved surface is smooth, but after chemical etching a fine Structure appears, with a great number of closely packed microcrystals of a dendritic shape. X-ray diffraction spectra of lamellae only show the reflections of the CuInS{sub 2} (112) and of the CuIn{sub 5}S{sub 8} (111) lattice planes, indicating a strongly oriented Structure. Depth profiles of CuInS{sub 2} lamellae investigated with X-ray photoelectron spectroscopy show the presence at the cleaved surface of Cu deficient phases like CuIn{sub 5}S{sub 8}, which are a few tens of nanometers thick. The lamellar growth mechanism is discussed on the basis of these findings. X-ray photoelectron spectroscopy and secondary ion mass spectrometry investigations show that the oxidation behavior of the lamellar material resembles that of traditional CuInX{sub 2} phases (X = S, Se).
Frank Mücklich - One of the best experts on this subject based on the ideXlab platform.
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Structuring of metallic bi- and tri-nano-layer films by laser interference irradiation: control of the Structure Depth
Applied Surface Science, 2005Co-Authors: Andrés Fabián Lasagni, Frank MücklichAbstract:Abstract A periodical structuring on bi-metallic thin layer films was performed by irradiation in air with an Nd:YAG laser operating in pulsed mode. The samples consist on Fe–Al, Cu–Al, Ni–Al and Fe–Al–Fe over a glass substrate. The influence of the laser fluence, the layer thickness, and the substrate on the Structure Depth (SD) was studied. A thermal simulation was carried out to estimate the temperature distribution and the quantities of the molten material in each layer. It was found that the maximal SD in the lower energy regime is reached at the threshold laser fluence value at which the topography type changes from a low to a high Structured profile type. In addition, it was found that as the thickness of the second layer and the difference between the melting points of the metallic layers increase, the Structure Depth also increases. In the case of bi-layer films, the structuring of the samples is conducted by the expansion of the Al and the glass–substrate at the interference peaks. Nevertheless, if a third metallic layer is placed over the substrate, the Structure Depth decreases as the thickness of this layer increases. This occurs because the third layer helps to evacuate the heat from the first two layers much faster than the glass substrate and therefore decreasing the Structure Depth.
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Study of the multilayer metallic films topography modified by laser interference irradiation
Applied Surface Science, 2004Co-Authors: Andrés Fabián Lasagni, Frank MücklichAbstract:Abstract The thin bimetallic film systems Fe–Al, Fe–Ni, Ti–Al, and Ti–Ni were irradiated using a laser interference pattern with laser fluence values from 50 to 250 mJ/cm2. The thermal simulation was carried out to analyze the topographical effects. It was found that according to the laser fluence value, three different types of topographies can be obtained. For lower laser fluence values, the molten material in the lower layer induces deformation over the upper one obtaining a periodic pattern with a Structure Depth in the order of the layer thickness. If the laser fluence is high enough so that the upper layer reaches the melting point, this last is broken obtaining a high Structured pattern consisting on a large depression and next two consecutive peaks. This threshold value can be estimated using the thermal simulation calculating the laser fluence at which the upper layer starts to melt. For higher laser fluence values, this pattern transforms into a periodical peak–valley Structure with high Structure Depth. In both last two cases, the material at the interference peaks is removed. A model is suggested for explaining this behavior.
Andrés Fabián Lasagni - One of the best experts on this subject based on the ideXlab platform.
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Fast and cost effective fabrication of microlens arrays for enhancing light out-coupling of organic light-emitting diodes
Materials Letters, 2019Co-Authors: Andre Stellmacher, Yuan Liu, Marcos Soldera, Andreas Rank, Sebastian Reineke, Andrés Fabián LasagniAbstract:Abstract The efficiency of organic light-emitting diodes (OLEDs) deposited on flat substrates is strongly limited by the total internal reflection at the air-substrate interface. An effective strategy to reduce the amount of substrate modes and enhance the light out-coupling into the air is attaching a microlens array (MLA) on the external surface of OLEDs. In this study, polymeric MLA with periods between 1.2 µm and 2.0 µm are patterned by plate-to-plate nano-imprint lithography using metallic stamps Structured by direct laser interference patterning. When MLA with a spatial period of 2.0 µm and a Structure Depth of 200 nm are employed on red, green and blue OLEDs, the external quantum efficiency is increased to 11.4%, 6.6% and 12.7%, respectively, due to a reduction of internally reflected radiation at the air-MLA-glass interfaces.
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Structuring of metallic bi- and tri-nano-layer films by laser interference irradiation: control of the Structure Depth
Applied Surface Science, 2005Co-Authors: Andrés Fabián Lasagni, Frank MücklichAbstract:Abstract A periodical structuring on bi-metallic thin layer films was performed by irradiation in air with an Nd:YAG laser operating in pulsed mode. The samples consist on Fe–Al, Cu–Al, Ni–Al and Fe–Al–Fe over a glass substrate. The influence of the laser fluence, the layer thickness, and the substrate on the Structure Depth (SD) was studied. A thermal simulation was carried out to estimate the temperature distribution and the quantities of the molten material in each layer. It was found that the maximal SD in the lower energy regime is reached at the threshold laser fluence value at which the topography type changes from a low to a high Structured profile type. In addition, it was found that as the thickness of the second layer and the difference between the melting points of the metallic layers increase, the Structure Depth also increases. In the case of bi-layer films, the structuring of the samples is conducted by the expansion of the Al and the glass–substrate at the interference peaks. Nevertheless, if a third metallic layer is placed over the substrate, the Structure Depth decreases as the thickness of this layer increases. This occurs because the third layer helps to evacuate the heat from the first two layers much faster than the glass substrate and therefore decreasing the Structure Depth.
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Study of the multilayer metallic films topography modified by laser interference irradiation
Applied Surface Science, 2004Co-Authors: Andrés Fabián Lasagni, Frank MücklichAbstract:Abstract The thin bimetallic film systems Fe–Al, Fe–Ni, Ti–Al, and Ti–Ni were irradiated using a laser interference pattern with laser fluence values from 50 to 250 mJ/cm2. The thermal simulation was carried out to analyze the topographical effects. It was found that according to the laser fluence value, three different types of topographies can be obtained. For lower laser fluence values, the molten material in the lower layer induces deformation over the upper one obtaining a periodic pattern with a Structure Depth in the order of the layer thickness. If the laser fluence is high enough so that the upper layer reaches the melting point, this last is broken obtaining a high Structured pattern consisting on a large depression and next two consecutive peaks. This threshold value can be estimated using the thermal simulation calculating the laser fluence at which the upper layer starts to melt. For higher laser fluence values, this pattern transforms into a periodical peak–valley Structure with high Structure Depth. In both last two cases, the material at the interference peaks is removed. A model is suggested for explaining this behavior.
Tomas Kohout - One of the best experts on this subject based on the ideXlab platform.
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non invasive geophysical investigation and thermodynamic analysis of a palsa in lapland northwest finland
arXiv: Geophysics, 2014Co-Authors: Tomas Kohout, Kai Rasmus, Matti Leppäranta, Ilkka S. O. Matero, Michal S BuckoAbstract:Non-invasive geophysical prospecting and a thermodynamic model were used to examine the Structure, Depth and lateral extent of the frozen core of a palsa near Lake Peeraj\"arvi, in northwest Finland. A simple thermodynamic model verified that the current climatic conditions in the study area allow sustainable palsa development. A ground penetrating radar (GPR) survey of the palsa under both winter and summer conditions revealed its internal Structure and the size of its frozen core. GPR imaging in summer detected the upper peat/core boundary, and imaging in winter detected a deep reflector that probably represents the lower core boundary. This indicates that only a combined summer and winter GPR survey completely reveals the lateral and vertical extent of the frozen core of the palsa. The core underlies the active layer at a Depth of ~0.6 m and extends to about 4 m Depth. Its lateral extent is ~15 m x ~30 m. The presence of the frozen core could also be traced as minima in surface temperature and ground conductivity measurements. These field methods and thermodynamic models can be utilized in studies of climate impact on Arctic wetlands.
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Non‐Invasive Geophysical Investigation and Thermodynamic Analysis of a Palsa in Lapland, Northwest Finland
Permafrost and Periglacial Processes, 2014Co-Authors: Tomas Kohout, Michał S. Bućko, Kai Rasmus, Matti Leppäranta, Ilkka S. O. MateroAbstract:Non-invasive geophysical prospecting and a thermodynamic model were used to examine the Structure, Depth and lateral extent of the frozen core of a palsa near Lake Peerajarvi in northwest Finland. A simple thermodynamic model verified that the current climatic conditions in the study area allow sustainable palsa development. A ground penetrating radar (GPR) survey of the palsa under both winter and summer conditions revealed its internal Structure and the size of its frozen core. GPR imaging in summer detected the upper peat/core boundary, and imaging in winter detected a deep reflector that probably represents the lower core boundary. This indicates that only a combined summer and winter GPR survey completely reveals the lateral and vertical extent of the frozen core of the palsa. The core underlies the active layer at a Depth of ~ 0.6 m and extends to about 4 m Depth. Its lateral extent is ~ 15 m x ~ 30 m. The presence of the frozen core could also be traced as minima in surface temperature and ground conductivity measurements. These field methods and thermodynamic models can be utilised in studies of climate impact on Arctic wetlands. Copyright © 2014 John Wiley & Sons, Ltd.
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non invasive geophysical investigation and thermodynamic analysis of a palsa in lapland northwest finland
Permafrost and Periglacial Processes, 2014Co-Authors: Tomas Kohout, Kai Rasmus, Matti Leppäranta, Ilkka S. O. Matero, Michal S BuckoAbstract:Non-invasive geophysical prospecting and a thermodynamic model were used to examine the Structure, Depth and lateral extent of the frozen core of a palsa near Lake Peerajarvi in northwest Finland. A simple thermodynamic model verified that the current climatic conditions in the study area allow sustainable palsa development. A ground penetrating radar (GPR) survey of the palsa under both winter and summer conditions revealed its internal Structure and the size of its frozen core. GPR imaging in summer detected the upper peat/core boundary, and imaging in winter detected a deep reflector that probably represents the lower core boundary. This indicates that only a combined summer and winter GPR survey completely reveals the lateral and vertical extent of the frozen core of the palsa. The core underlies the active layer at a Depth of ~ 0.6 m and extends to about 4 m Depth. Its lateral extent is ~ 15 m x ~ 30 m. The presence of the frozen core could also be traced as minima in surface temperature and ground conductivity measurements. These field methods and thermodynamic models can be utilised in studies of climate impact on Arctic wetlands. Copyright © 2014 John Wiley & Sons, Ltd.
